Free vibration of a circular cylindrical double-shell system closed by end plates

An analysis is presented for the free vibration of a circular cylindrical double-shell system closed by end plates. The governing equations of vibration of an inner or an outer shell and of an end plate are written as matrix differential equations of the first order by using the transfer matrices of the shell and the plate. Once the matrices have been determined, the entire structure matrix is obtained by forming the product of the transfer matrices of the shell and the plate and the point matrices at the joints, and the frequency equation of the system is derived with terms of the elements of the structure matrix. The method has been applied to a uniform thickness double-shell system composed of two co-axial shells and two annular plates, and results of numerical calculations of the natural frequencies and the mode shapes of vibration are presented.